Peptide bond formation on the ribosome: structure and mechanism |
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Authors: | Rodnina Marina V Wintermeyer Wolfgang |
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Institution: | Institutes of Physical Biochemistry and Molecular Biology, University of Witten/Herdecke, Stockumer Strasse 10, 58448, Witten, Germany. rodnina@uni-wh.de |
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Abstract: | The peptidyl transferase reaction on the ribosome is catalyzed by RNA. Pre-steady-state kinetic studies using Escherichia coli ribosomes suggest that catalysis (>10(5)-fold overall acceleration) is, to a large part, a result of substrate positioning, in agreement with crystal structures of large ribosomal subunits with bound substrate or product analogs. The rate of peptide bond formation is inhibited approximately 100-fold by protonation of a single ribosomal group with a pK(a) of 7.5, indicating general acid-base catalysis and/or a pH-dependent conformational change within the active site. According to the kinetics of mutant ribosomes, these effects may be attributed to a candidate catalytic base (A2451) suggested by the crystal structure. |
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